This invention relates to methods and apparatus for electrophoresis of biomolecules.
It is common in the biotechnology industry and in research laboratories to electrophorese biomolecules. Such electrophoresis is performed generally within a gel matrix. The matrix is placed in electrical contact with at least two electrodes (an anode and a cathode). An electrophoresis buffer is used both within and outside of the matrix to provide electrical contact between the electrodes and the matrix. The buffer may contact not only the ends of the matrix but also may be positioned against at least one surface of the gel, e.g., against the top surface of a horizontal gel. Such gels are used, for example, in fractionation of DNA restriction fragments and PCR products, as well as in separation of other high molecular weight materials such as RNA and proteins. For example, Kreisher et al., U.S. Pat. No. 4,576,693 describes an electrophoresis apparatus and method for fabricating a gel matrix. In general, two sheets or pieces of glass or plastic are placed near to each other with spacing devices designed to create a space between the two plates. A gel matrix-forming material is then poured within the space. Buffer is contacted with the two ends of the gel matrix and material of high or low molecular weight can be electrophoresed through that matrix.
Sugihara et al., U.S. Pat. Nos. 4,834,854, 4,844,786 and 5,190,629 describe methods for forming a matrix having a concentration gradient of matrix materials along its length, having varying thicknesses along its length, or having a combination of a gradual change in thickness of matrix and change in concentration of matrix materials. Such variations in matrix materials are said to aid separation of molecules electrophoresed within the matrix.
Valmet, U.S. Pat. No. 3,616,456, describes a device for isoelectric separation of ampholytes.
Brefka, U.S. Pat. No. 3,932,263, describes an electrophoresis slide mounting means; and Firth, U.S. Pat. No. 5,232,856, describes an electroporation device.
Biggin et al., 80 Proc. Natl. Acad. Sci. USA, 3963, 1983, describes buffer gradient gels allegedly useful to aid in rapid DNA sequence determination.